Realtime Library                                     sem_init(3R)



NAME
     sem_init - initialize an unnamed semaphore

SYNOPSIS
     cc [ flag ... ] file ...  -lposix4 [ library ... ]

     #include <semaphore.h>

     int sem_init(sem_t *sem, int pshared, unsigned int value );

DESCRIPTION
     The sem_init() function is used to  initialize  the  unnamed
     semaphore  referred  to by sem to value.  This semaphore may
     be   used   in    subsequent    calls    to    sem_wait(3R),
     sem_trywait(3R),  sem_post(3R),  and  sem_destroy(3R).  This
     semaphore remains usable until the semaphore is destroyed.

     If pshared is  non-zero,  then  the  semaphore  is  sharable
     between  processes.   If  the  semaphore is not being shared
     between processes, the application should set pshared to 0.

RETURN VALUES
     If successful, sem_init()  returns  0  and  initializes  the
     semaphore  in sem; otherwise it returns -1 and sets errno to
     indicate the error condition.

ERRORS
     EINVAL      The value argument exceeds SEM_VALUE_MAX.

     ENOSPC      A resource required to initialize the  semaphore
                 has   been  exhausted,  or  the  resources  have
                 reached the limit on semaphores (SEM_NSEMS_MAX).

     ENOSYS      The sem_init() function is not supported.

     EPERM       The  calling  process  lacks   the   appropriate
                 privileges to initialize the semaphore.

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

     __________________________________
    | ATTRIBUTE TYPE|  ATTRIBUTE VALUE|
    |_______________|__________________|_
    | MT-Level      |  MT-Safe        |
    |_______________|_________________|

SEE ALSO
     sem_destroy(3R), sem_post(3R), sem_wait(3R), attributes(5)